The present invention provides an automated system for controlling the opening and closing of drawers in a cabinet. The invention is especially useful in medical applications, wherein one desires to dispense controlled amounts of medications to patients. The invention can also be used in other contexts.
In a hospital environment, it is often desired to dispense a specific number of items automatically, where the items are selected from a variety of possible choices. Dispensing machines have been known in non-medical applications, such as in the vending of candy, soda, and cigarettes, and in the dispensing of currency through automated teller machines. Unlike the latter devices, which generally dispense articles having a fairly consistent size and shape, a hospital environment requires the dispensing of many different kinds of items having many different sizes. For example, a dispensing device used in a hospital might dispense not only pills but also hypodermic needles and bottles, all of differing sizes.
It is possible to dispense a wide range of packages simply by providing a large number of different-sized drawers which are individually opened on command. Packages of different sizes could be stored within different drawers. The drawers can be subdivided to allow multiple packages or multiple doses of drugs to be stored within a single drawer.
Many devices have been developed for dispensing multiple doses of medications to patients, especially in hospital environment. Such devices often take the form of cabinets having a plurality of drawers. Examples of such cabinets appear in U.S. Pat. Nos. 5,139,321, 4,813,753, 4,518,208, 4,588,237, 4,019,793, 4,114,965, and 4,127,311.
Various devices have been developed which automate, or partially automate, the operation of cabinets containing medications. For example, U.S. Pat. No. 5,047,948 shows an automated medicine dispenser in which a stop in the cabinet limits the movement of a door to restrict access to drugs by the patient.
Other patents showing computer-controlled medicine dispensing devices include U.S. Pat. Nos. 5,159,581 and 4,967,928. Similarly, U.S. Pat. No. 4,267,942 shows a partially-automated drug dispensing cabinet having structure which limits access to the items stored inside the cabinet.
U.S. Pat. No. 5,014,875 describes an automated drug dispensing unit comprising a cabinet having multiple drawers. The unit is programmed to unlock one drawer at a time. One or more drawers hold trays having multiple compartments, and each tray rotates under a plate having an opening, thus permitting access to only one compartment of the tray.
Because of the wide variety of items stored in a medical cabinet, it is advantageous to provide a cabinet having a plurality of drawers, all of the drawers being of the same size, wherein each drawer is limited in its travel to allow access only to a predetermined number of drawer compartments. For example, if a drawer containing twenty hypodermic needles is full, and the operator requires two units, the drawer could be opened so as to expose only the first two compartments. If the next user requires one unit, the drawer would then open to expose the first three compartments, since the first two would already be empty. A computer would keep a record of the contents remaining in each drawer so as to take the proper action on the next request.
There are many mechanisms which could be used to limit the opening of a drawer to a specific distance. However, in a typical cabinet for dispensing medicines, as used in a hospital, there may be up to 72 drawers, and the cost of providing individual control mechanisms for each drawer can be prohibitive.
The present invention therefore provides a mechanism which enables automatic opening of one selected drawer of a cabinet, and which opens that drawer to a predetermined distance. The drawer operating system of the present invention does not require separate controls for each drawer, but instead uses controls which are common to a plurality of drawers. Thus, the present invention provides a practical solution to the problem of automatic dispensing of medications.